CITEL DS220S-24DC DC Power Din Rail Surge Protector for 24Vdc Power Supplies Datasheet Contact Us DC Network: 24Vdc, 2W+G Application: 5G Radio, Rectifier, Charge Controller In order to limit the effects of lightning or switching transients to acceptable levels for critical equipment and installations, the most effective solution is to install a protection device against these events. We call this an "SPD" (Surge Protective Device), they are deployed into the power network at the input to a distribution bus or directly at a sensitive load. The purpose is to harmlessly divert damaging surges away from your sensitive equipment before any disruption occurs.